C++ PetscStrlen函数代码示例

/*@C
   PetscDrawAppendTitle - Appends to the title of a PetscDraw context.

   Not collective (any processor or all can call this)

   Input Parameters:
+  draw - the graphics context
-  title - the title

   Note:
   A copy of the string is made, so you may destroy the
   title string after calling this routine.

   Level: advanced

.seealso: PetscDrawSetTitle(), PetscDrawGetTitle()
@*/
PetscErrorCode  PetscDrawAppendTitle(PetscDraw draw,const char title[])
{
  PetscErrorCode ierr;
  size_t         len1,len2,len;
  char           *newtitle;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(draw,PETSC_DRAW_CLASSID,1);
  if (!title) PetscFunctionReturn(0);

  if (draw->title) {
    ierr = PetscStrlen(title,&len1);CHKERRQ(ierr);
    ierr = PetscStrlen(draw->title,&len2);CHKERRQ(ierr);
    len  = len1 + len2;
    ierr = PetscMalloc1((len + 1),&newtitle);CHKERRQ(ierr);
    ierr = PetscStrcpy(newtitle,draw->title);CHKERRQ(ierr);
    ierr = PetscStrcat(newtitle,title);CHKERRQ(ierr);
    ierr = PetscFree(draw->title);CHKERRQ(ierr);

    draw->title = newtitle;
  } else {
    ierr = PetscStrallocpy(title,&draw->title);CHKERRQ(ierr);
  }
  if (draw->ops->settitle) {
    ierr = (*draw->ops->settitle)(draw,draw->title);CHKERRQ(ierr);
  }
  PetscFunctionReturn(0);
}

static PetscErrorCode PetscDrawString_X(PetscDraw draw,PetscReal x,PetscReal  y,int c,const char chrs[])
{
  PetscErrorCode ierr;
  int            xx,yy;
  size_t         len;
  PetscDraw_X    *XiWin = (PetscDraw_X*)draw->data;
  char           *substr;
  PetscToken     token;

  PetscFunctionBegin;
  xx = XTRANS(draw,XiWin,x);  yy = YTRANS(draw,XiWin,y);
  PetscDrawXiSetColor(XiWin,c);

  ierr = PetscTokenCreate(chrs,'\n',&token);CHKERRQ(ierr);
  ierr = PetscTokenFind(token,&substr);CHKERRQ(ierr);
  ierr = PetscStrlen(substr,&len);CHKERRQ(ierr);
  XDrawString(XiWin->disp,PetscDrawXiDrawable(XiWin),XiWin->gc.set,xx,yy - XiWin->font->font_descent,substr,len);
  ierr = PetscTokenFind(token,&substr);CHKERRQ(ierr);
  while (substr) {
    yy  += 4*XiWin->font->font_descent;
    ierr = PetscStrlen(substr,&len);CHKERRQ(ierr);
    XDrawString(XiWin->disp,PetscDrawXiDrawable(XiWin),XiWin->gc.set,xx,yy - XiWin->font->font_descent,substr,len);
    ierr = PetscTokenFind(token,&substr);CHKERRQ(ierr);
  }
  ierr = PetscTokenDestroy(&token);CHKERRQ(ierr);

  PetscFunctionReturn(0);
}

/*@C
    PetscGetHostName - Returns the name of the host. This attempts to
    return the entire Internet name. It may not return the same name
    as MPI_Get_processor_name().

    Not Collective

    Input Parameter:
.   nlen - length of name

    Output Parameter:
.   name - contains host name.  Must be long enough to hold the name
           This is the fully qualified name, including the domain.

    Level: developer

    Concepts: machine name
    Concepts: host name

   Fortran Version:
   In Fortran this routine has the format

$       character*(64) name
$       call PetscGetHostName(name,ierr)

.seealso: PetscGetUserName(),PetscGetArchType()
@*/
PetscErrorCode  PetscGetHostName(char name[],size_t nlen)
{
    char           *domain;
    PetscErrorCode ierr;
#if defined(PETSC_HAVE_UNAME) && !defined(PETSC_HAVE_GETCOMPUTERNAME)
    struct utsname utname;
#endif

    PetscFunctionBegin;
#if defined(PETSC_HAVE_GETCOMPUTERNAME)
    {
        size_t nnlen = nlen;
        GetComputerName((LPTSTR)name,(LPDWORD)(&nnlen));
    }
#elif defined(PETSC_HAVE_UNAME)
    uname(&utname);
    ierr = PetscStrncpy(name,utname.nodename,nlen);
    CHKERRQ(ierr);
#elif defined(PETSC_HAVE_GETHOSTNAME)
    gethostname(name,nlen);
#elif defined(PETSC_HAVE_SYSINFO_3ARG)
    sysinfo(SI_HOSTNAME,name,nlen);
#endif
    /* if there was not enough room then system call will not null terminate name */
    name[nlen-1] = 0;

    /* See if this name includes the domain */
    ierr = PetscStrchr(name,'.',&domain);
    CHKERRQ(ierr);
    if (!domain) {
        size_t l,ll;
        ierr = PetscStrlen(name,&l);
        CHKERRQ(ierr);
        if (l == nlen-1) PetscFunctionReturn(0);
        name[l++] = '.';
        name[l]   = 0;
#if defined(PETSC_HAVE_SYSINFO_3ARG)
        sysinfo(SI_SRPC_DOMAIN,name+l,nlen-l);
#elif defined(PETSC_HAVE_GETDOMAINNAME)
        if (getdomainname(name+l,nlen - l)) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SYS,"getdomainname()");
#endif
        /* check if domain name is not a dnsdomainname and nuke it */
        ierr = PetscStrlen(name,&ll);
        CHKERRQ(ierr);
        if (ll > 4) {
            const char *suffixes[] = {".edu",".com",".net",".org",".mil",0};
            PetscInt   index;
            ierr = PetscStrendswithwhich(name,suffixes,&index);
            CHKERRQ(ierr);
            if (!suffixes[index]) {
                ierr      = PetscInfo1(0,"Rejecting domainname, likely is NIS %s\n",name);
                CHKERRQ(ierr);
                name[l-1] = 0;
            }
        }
    }
    PetscFunctionReturn(0);
}

PetscErrorCode MatLUFactorNumeric_Matlab(Mat F,Mat A,const MatFactorInfo *info)
{
    PetscErrorCode ierr;
    size_t         len;
    char           *_A,*name;
    PetscReal      dtcol = info->dtcol;

    PetscFunctionBegin;
    if (F->factortype == MAT_FACTOR_ILU || info->dt > 0) {
        /* the ILU form is not currently registered */
        if (info->dtcol == PETSC_DEFAULT) dtcol = .01;
        F->ops->solve = MatSolve_Matlab;
        F->factortype = MAT_FACTOR_LU;

        ierr = PetscMatlabEnginePut(PETSC_MATLAB_ENGINE_(PetscObjectComm((PetscObject)A)),(PetscObject)A);
        CHKERRQ(ierr);
        _A   = ((PetscObject)A)->name;
        ierr = PetscMatlabEngineEvaluate(PETSC_MATLAB_ENGINE_(PetscObjectComm((PetscObject)A)),"info_%s = struct('droptol',%g,'thresh',%g);",_A,info->dt,dtcol);
        CHKERRQ(ierr);
        ierr = PetscMatlabEngineEvaluate(PETSC_MATLAB_ENGINE_(PetscObjectComm((PetscObject)A)),"[l_%s,u_%s,p_%s] = luinc(%s',info_%s);",_A,_A,_A,_A,_A);
        CHKERRQ(ierr);
        ierr = PetscMatlabEngineEvaluate(PETSC_MATLAB_ENGINE_(PetscObjectComm((PetscObject)A)),"%s = 0;",_A);
        CHKERRQ(ierr);

        ierr = PetscStrlen(_A,&len);
        CHKERRQ(ierr);
        ierr = PetscMalloc1(len+2,&name);
        CHKERRQ(ierr);
        sprintf(name,"_%s",_A);
        ierr = PetscObjectSetName((PetscObject)F,name);
        CHKERRQ(ierr);
        ierr = PetscFree(name);
        CHKERRQ(ierr);
    } else {
        ierr = PetscMatlabEnginePut(PETSC_MATLAB_ENGINE_(PetscObjectComm((PetscObject)A)),(PetscObject)A);
        CHKERRQ(ierr);
        _A   = ((PetscObject)A)->name;
        ierr = PetscMatlabEngineEvaluate(PETSC_MATLAB_ENGINE_(PetscObjectComm((PetscObject)A)),"[l_%s,u_%s,p_%s] = lu(%s',%g);",_A,_A,_A,_A,dtcol);
        CHKERRQ(ierr);
        ierr = PetscMatlabEngineEvaluate(PETSC_MATLAB_ENGINE_(PetscObjectComm((PetscObject)A)),"%s = 0;",_A);
        CHKERRQ(ierr);
        ierr = PetscStrlen(_A,&len);
        CHKERRQ(ierr);
        ierr = PetscMalloc1(len+2,&name);
        CHKERRQ(ierr);
        sprintf(name,"_%s",_A);
        ierr = PetscObjectSetName((PetscObject)F,name);
        CHKERRQ(ierr);
        ierr = PetscFree(name);
        CHKERRQ(ierr);

        F->ops->solve = MatSolve_Matlab;
    }
    PetscFunctionReturn(0);
}

/*@C
   PetscDrawSetSave - Saves images produced in a PetscDraw into a file

   Collective on PetscDraw

   Input Parameter:
+  draw      - the graphics context
.  filename  - name of the file, if .ext then uses name of draw object plus .ext using .ext to determine the image type
-  movieext  - if not NULL, produces a movie of all the images

   Options Database Command:
+  -draw_save  <filename>  - filename could be name.ext or .ext (where .ext determines the type of graphics file to save, for example .png)
.  -draw_save_movie <.ext> - saves a movie to filename.ext
.  -draw_save_final_image [optional filename] - saves the final image displayed in a window
-  -draw_save_single_file - saves each new image in the same file, normally each new image is saved in a new file with filename/filename_%d.ext

   Level: intermediate

   Concepts: X windows^graphics

   Notes: You should call this BEFORE creating your image and calling PetscDrawSave().
   The supported image types are .png, .gif, .jpg, and .ppm (PETSc chooses the default in that order).
   Support for .png images requires configure --with-libpng.
   Support for .gif images requires configure --with-giflib.
   Support for .jpg images requires configure --with-libjpeg.
   Support for .ppm images is built-in. The PPM format has no compression (640x480 pixels ~ 900 KiB).
   The ffmpeg utility must be in your path to make the movie.

.seealso: PetscDrawSetFromOptions(), PetscDrawCreate(), PetscDrawDestroy(), PetscDrawSetSaveFinalImage()
@*/
PetscErrorCode  PetscDrawSetSave(PetscDraw draw,const char filename[],const char movieext[])
{
  const char     *savename = NULL;
  const char     *imageext = NULL;
  char           buf[PETSC_MAX_PATH_LEN];
  PetscErrorCode ierr;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(draw,PETSC_DRAW_CLASSID,1);
  if (filename) PetscValidCharPointer(filename,2);
  if (movieext) PetscValidCharPointer(movieext,2);

  /* determine save filename and image extension */
  if (filename && filename[0]) {
    ierr = PetscStrchr(filename,'.',(char **)&imageext);CHKERRQ(ierr);
    if (!imageext) savename = filename;
    else if (imageext != filename) {
      size_t l1 = 0,l2 = 0;
      ierr = PetscStrlen(filename,&l1);CHKERRQ(ierr);
      ierr = PetscStrlen(imageext,&l2);CHKERRQ(ierr);
      ierr = PetscStrncpy(buf,filename,l1-l2+1);CHKERRQ(ierr);
      savename = buf;
    }
  }

  if (!savename) {ierr = PetscObjectGetName((PetscObject)draw,&savename);CHKERRQ(ierr);}
  ierr = PetscDrawImageCheckFormat(&imageext);CHKERRQ(ierr);
  if (movieext) {ierr = PetscDrawMovieCheckFormat(&movieext);CHKERRQ(ierr);}
  if (movieext) draw->savesinglefile = PETSC_FALSE; /* otherwise we cannot generage movies */

  if (draw->savesinglefile) {
    ierr = PetscInfo2(NULL,"Will save image to file %s%s\n",savename,imageext);CHKERRQ(ierr);
  } else {
    ierr = PetscInfo3(NULL,"Will save images to file %s/%s_%%d%s\n",savename,savename,imageext);CHKERRQ(ierr);
  }
  if (movieext) {
    ierr = PetscInfo2(NULL,"Will save movie to file %s%s\n",savename,movieext);CHKERRQ(ierr);
  }

  draw->savefilecount = 0;
  ierr = PetscFree(draw->savefilename);CHKERRQ(ierr);
  ierr = PetscFree(draw->saveimageext);CHKERRQ(ierr);
  ierr = PetscFree(draw->savemovieext);CHKERRQ(ierr);
  ierr = PetscStrallocpy(savename,&draw->savefilename);CHKERRQ(ierr);
  ierr = PetscStrallocpy(imageext,&draw->saveimageext);CHKERRQ(ierr);
  ierr = PetscStrallocpy(movieext,&draw->savemovieext);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

/*
    Removes trailing zeros
*/
PetscErrorCode PetscStripTrailingZeros(char *buf)
{
  PetscErrorCode ierr;
  char           *found;
  size_t         i,n,m = PETSC_MAX_INT;

  PetscFunctionBegin;
  /* if there is an e in string DO NOT strip trailing zeros */
  ierr = PetscStrchr(buf,'e',&found);CHKERRQ(ierr);
  if (found) PetscFunctionReturn(0);

  ierr = PetscStrlen(buf,&n);CHKERRQ(ierr);
  /* locate decimal point */
  for (i=0; i<n; i++) {
    if (buf[i] == '.') {m = i; break;}
  }
  /* if not decimal point then no zeros to remove */
  if (m == PETSC_MAX_INT) PetscFunctionReturn(0);
  /* start at right end of string removing 0s */
  for (i=n-1; i>m; i++) {
    if (buf[i] != '0') PetscFunctionReturn(0);
    buf[i] = 0;
  }
  PetscFunctionReturn(0);
}

PetscErrorCode PetscViewerFileSetName_MPIIO(PetscViewer viewer,const char name[])
{
  PetscMPIInt        rank;
  PetscErrorCode     ierr;
  size_t             len;
  PetscViewer_Binary *vbinary = (PetscViewer_Binary*)viewer->data;
  char               *gz;
  PetscBool          found;
  PetscFileMode      type = vbinary->btype;

  PetscFunctionBegin;
  if (type == (PetscFileMode) -1) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ORDER,"Must call PetscViewerFileSetMode() before PetscViewerFileSetName()");
  ierr = PetscViewerFileClose_MPIIO(viewer);CHKERRQ(ierr);
  ierr = PetscOptionsGetBool(((PetscObject)viewer)->prefix,"-viewer_binary_skip_info",&vbinary->skipinfo,NULL);CHKERRQ(ierr);
  ierr = PetscOptionsGetBool(((PetscObject)viewer)->prefix,"-viewer_binary_skip_options",&vbinary->skipoptions,NULL);CHKERRQ(ierr);

  ierr = MPI_Comm_rank(PetscObjectComm((PetscObject)viewer),&rank);CHKERRQ(ierr);
  ierr = PetscStrallocpy(name,&vbinary->filename);CHKERRQ(ierr);

  vbinary->storecompressed = PETSC_FALSE;

  /* only first processor opens file if writeable */
  if (type == FILE_MODE_READ) {
    MPI_File_open(PetscObjectComm((PetscObject)viewer),vbinary->filename,MPI_MODE_RDONLY,MPI_INFO_NULL,&vbinary->mfdes);CHKERRQ(ierr);
  } else if (type == FILE_MODE_WRITE) {
    MPI_File_open(PetscObjectComm((PetscObject)viewer),vbinary->filename,MPI_MODE_WRONLY | MPI_MODE_CREATE,MPI_INFO_NULL,&vbinary->mfdes);CHKERRQ(ierr);
  }

  /*
      try to open info file: all processors open this file if read only

      Below is identical code to the code for Binary above, should be put in seperate routine
  */
  if (!vbinary->skipinfo && (!rank || type == FILE_MODE_READ)) {
    char infoname[PETSC_MAX_PATH_LEN],iname[PETSC_MAX_PATH_LEN];

    ierr = PetscStrcpy(infoname,name);CHKERRQ(ierr);
    /* remove .gz if it ends library name */
    ierr = PetscStrstr(infoname,".gz",&gz);CHKERRQ(ierr);
    if (gz) {
      ierr = PetscStrlen(gz,&len);CHKERRQ(ierr);
      if (len == 3) *gz = 0;
    }

    ierr = PetscStrcat(infoname,".info");CHKERRQ(ierr);
    ierr = PetscFixFilename(infoname,iname);CHKERRQ(ierr);
    if (type == FILE_MODE_READ) {
      ierr = PetscFileRetrieve(PetscObjectComm((PetscObject)viewer),iname,infoname,PETSC_MAX_PATH_LEN,&found);CHKERRQ(ierr);
      ierr = PetscOptionsInsertFile(PetscObjectComm((PetscObject)viewer),infoname,PETSC_FALSE);CHKERRQ(ierr);
    } else {
      vbinary->fdes_info = fopen(infoname,"w");
      if (!vbinary->fdes_info) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_FILE_OPEN,"Cannot open .info file %s for writing",infoname);
    }
  }

#if defined(PETSC_USE_LOG)
  PetscLogObjectState((PetscObject)viewer,"File: %s",name);
#endif
  PetscFunctionReturn(0);
}

static PetscErrorCode CreateMesh(MPI_Comm comm, AppCtx *ctx, DM *dm)
{
  PetscInt       dim         = ctx->dim;
  PetscBool      cellSimplex = ctx->cellSimplex;
  const char    *filename    = ctx->filename;
  const PetscInt cells[3]    = {1, 1, 1};
  size_t         len;
  PetscMPIInt    rank, size;
  PetscErrorCode ierr;

  PetscFunctionBegin;
  ierr = MPI_Comm_rank(comm, &rank);CHKERRQ(ierr);
  ierr = MPI_Comm_size(comm, &size);CHKERRQ(ierr);
  ierr = PetscStrlen(filename, &len);CHKERRQ(ierr);
  if (len) {ierr = DMPlexCreateFromFile(comm, filename, PETSC_TRUE, dm);CHKERRQ(ierr);}
  else     {ierr = DMPlexCreateBoxMesh(comm, dim, cellSimplex, cells, NULL, NULL, NULL, PETSC_TRUE, dm);CHKERRQ(ierr);}
  {
    DM               distributedMesh = NULL;
    PetscPartitioner part;

    ierr = DMPlexGetPartitioner(*dm, &part);CHKERRQ(ierr);
    ierr = PetscPartitionerSetFromOptions(part);CHKERRQ(ierr);

    /* Distribute mesh over processes */
    ierr = DMPlexDistribute(*dm, 0, NULL, &distributedMesh);CHKERRQ(ierr);
    if (distributedMesh) {
      ierr = DMDestroy(dm);CHKERRQ(ierr);
      *dm  = distributedMesh;
    }
  }
  ierr = PetscObjectSetName((PetscObject) *dm, "Mesh");CHKERRQ(ierr);
  ierr = DMSetFromOptions(*dm);CHKERRQ(ierr);
  ierr = DMViewFromOptions(*dm, NULL, "-dm_view");CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

/*
      Removes the plus in something like 1.1e+2 or 1.1e+02
*/
PetscErrorCode PetscStripZerosPlus(char *buf)
{
  PetscErrorCode ierr;
  size_t         i,j,n;

  PetscFunctionBegin;
  ierr = PetscStrlen(buf,&n);CHKERRQ(ierr);
  if (n<5) PetscFunctionReturn(0);
  for (i=1; i<n-2; i++) {
    if (buf[i] == '+') {
      if (buf[i+1] == '0') {
        for (j=i+1; j<n; j++) buf[j-1] = buf[j+1];
        PetscFunctionReturn(0);
      } else {
        for (j=i+1; j<n+1; j++) buf[j-1] = buf[j];
        PetscFunctionReturn(0);
      }
    } else if (buf[i] == '-') {
      if (buf[i+1] == '0') {
        for (j=i+1; j<n; j++) buf[j] = buf[j+1];
        PetscFunctionReturn(0);
      }
    }
  }
  PetscFunctionReturn(0);
}

/*@C
     PetscVFPrintf -  All PETSc standard out and error messages are sent through this function; so, in theory, this can
        can be replaced with something that does not simply write to a file.

      To use, write your own function for example,
$PetscErrorCode mypetscvfprintf(FILE *fd,const char format[],va_list Argp)
${
$  PetscErrorCode ierr;
$
$  PetscFunctionBegin;
$   if (fd != stdout && fd != stderr) {  handle regular files
$      ierr = PetscVFPrintfDefault(fd,format,Argp);CHKERR(ierr);
$  } else {
$     char   buff[BIG];
$     size_t length;
$     ierr = PetscVSNPrintf(buff,BIG,format,&length,Argp);CHKERRQ(ierr);
$     now send buff to whatever stream or whatever you want
$ }
$ PetscFunctionReturn(0);
$}
then before the call to PetscInitialize() do the assignment
$    PetscVFPrintf = mypetscvfprintf;

      Notes: For error messages this may be called by any process, for regular standard out it is
          called only by process 0 of a given communicator

      Developer Notes: this could be called by an error handler, if that happens then a recursion of the error handler may occur
                       and a crash

  Level:  developer

.seealso: PetscVSNPrintf(), PetscErrorPrintf()

@*/
PetscErrorCode  PetscVFPrintfDefault(FILE *fd,const char *format,va_list Argp)
{
  char           *newformat;
  char           formatbuf[8*1024];
  size_t         oldLength;
  PetscErrorCode ierr;

  PetscFunctionBegin;
  ierr = PetscStrlen(format, &oldLength);CHKERRQ(ierr);
  if (oldLength < 8*1024) {
    newformat = formatbuf;
    oldLength = 8*1024-1;
  } else {
    oldLength = PETSC_MAX_LENGTH_FORMAT(oldLength);
    ierr      = PetscMalloc(oldLength * sizeof(char), &newformat);CHKERRQ(ierr);
  }
  ierr = PetscFormatConvert(format,newformat,oldLength);CHKERRQ(ierr);

#if defined(PETSC_HAVE_VFPRINTF_CHAR)
  vfprintf(fd,newformat,(char*)Argp);
#else
  vfprintf(fd,newformat,Argp);
#endif
  fflush(fd);
  if (oldLength >= 8*1024) {
    ierr = PetscFree(newformat);CHKERRQ(ierr);
  }
  PetscFunctionReturn(0);
}

PetscErrorCode  PetscViewerFileSetName_VTK(PetscViewer viewer,const char name[])
{
  PetscViewer_VTK *vtk = (PetscViewer_VTK*)viewer->data;
  PetscErrorCode  ierr;
  PetscBool       isvtk,isvts,isvtu,isvtr;
  size_t          len;

  PetscFunctionBegin;
  ierr = PetscViewerFlush(viewer);CHKERRQ(ierr);
  ierr = PetscFree(vtk->filename);CHKERRQ(ierr);
  ierr = PetscStrlen(name,&len);CHKERRQ(ierr);
  ierr = PetscStrcasecmp(name+len-4,".vtk",&isvtk);CHKERRQ(ierr);
  ierr = PetscStrcasecmp(name+len-4,".vts",&isvts);CHKERRQ(ierr);
  ierr = PetscStrcasecmp(name+len-4,".vtu",&isvtu);CHKERRQ(ierr);
  ierr = PetscStrcasecmp(name+len-4,".vtr",&isvtr);CHKERRQ(ierr);
  if (isvtk) {
    if (viewer->format == PETSC_VIEWER_DEFAULT) {ierr = PetscViewerSetFormat(viewer,PETSC_VIEWER_ASCII_VTK);CHKERRQ(ierr);}
    if (viewer->format != PETSC_VIEWER_ASCII_VTK) SETERRQ2(PetscObjectComm((PetscObject)viewer),PETSC_ERR_ARG_INCOMP,"Cannot use file '%s' with format %s, should have '.vtk' extension",name,PetscViewerFormats[viewer->format]);
  } else if (isvts) {
    if (viewer->format == PETSC_VIEWER_DEFAULT) {ierr = PetscViewerSetFormat(viewer,PETSC_VIEWER_VTK_VTS);CHKERRQ(ierr);}
    if (viewer->format != PETSC_VIEWER_VTK_VTS) SETERRQ2(PetscObjectComm((PetscObject)viewer),PETSC_ERR_ARG_INCOMP,"Cannot use file '%s' with format %s, should have '.vts' extension",name,PetscViewerFormats[viewer->format]);
  } else if (isvtu) {
    if (viewer->format == PETSC_VIEWER_DEFAULT) {ierr = PetscViewerSetFormat(viewer,PETSC_VIEWER_VTK_VTU);CHKERRQ(ierr);}
    if (viewer->format != PETSC_VIEWER_VTK_VTU) SETERRQ2(PetscObjectComm((PetscObject)viewer),PETSC_ERR_ARG_INCOMP,"Cannot use file '%s' with format %s, should have '.vtu' extension",name,PetscViewerFormats[viewer->format]);
  } else if (isvtr) {
    if (viewer->format == PETSC_VIEWER_DEFAULT) {ierr = PetscViewerSetFormat(viewer,PETSC_VIEWER_VTK_VTR);CHKERRQ(ierr);}
    if (viewer->format != PETSC_VIEWER_VTK_VTR) SETERRQ2(PetscObjectComm((PetscObject)viewer),PETSC_ERR_ARG_INCOMP,"Cannot use file '%s' with format %s, should have '.vtr' extension",name,PetscViewerFormats[viewer->format]);
  } else SETERRQ1(PetscObjectComm((PetscObject)viewer),PETSC_ERR_ARG_UNKNOWN_TYPE,"File '%s' has unrecognized extension",name);
  ierr = PetscStrallocpy(name,&vtk->filename);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

PetscErrorCode CreateMesh(MPI_Comm comm, AppCtx *user, DM *dm)
{
  const char    *filename = user->filename;
  PetscInt       dim      = user->dim;
  size_t         len;
  PetscErrorCode ierr;

  PetscFunctionBegin;
  ierr = PetscStrlen(filename, &len);CHKERRQ(ierr);
  if (!len) {ierr = DMPlexCreateBoxMesh(comm, dim, PETSC_TRUE, dm);CHKERRQ(ierr);}
  else      {ierr = DMPlexCreateFromFile(comm, filename, PETSC_TRUE, dm);CHKERRQ(ierr);}
  ierr = DMViewFromOptions(*dm, NULL, "-orig_dm_view");CHKERRQ(ierr);
  {
    DM distributedMesh = NULL;

    ierr = DMPlexDistribute(*dm, 0, NULL, &distributedMesh);CHKERRQ(ierr);
    if (distributedMesh) {
      ierr = DMDestroy(dm);CHKERRQ(ierr);
      *dm  = distributedMesh;
      ierr = DMViewFromOptions(*dm, NULL, "-dist_dm_view");CHKERRQ(ierr);
    }
  }
  ierr = DMSetFromOptions(*dm);CHKERRQ(ierr);
  if (user->uninterpolate) {
    DM udm = NULL;

    ierr = DMPlexUninterpolate(*dm, &udm);CHKERRQ(ierr);
    ierr = DMDestroy(dm);CHKERRQ(ierr);
    *dm  = udm;
    ierr = DMViewFromOptions(*dm, NULL, "-un_dm_view");CHKERRQ(ierr);
  }
  ierr = PetscObjectSetName((PetscObject) *dm, "Test Mesh");CHKERRQ(ierr);
  ierr = DMViewFromOptions(*dm, NULL, "-dm_view");CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

static PetscErrorCode PetscDrawSave_SAWs(PetscDraw draw)
{
  PetscImageList image;
  char           body[4096];
  size_t         len = 0;
  PetscErrorCode ierr;

  PetscFunctionBegin;
  if (!draw->savefilename) PetscFunctionReturn(0);
  ierr = PetscImageListAdd(draw->savefilename,draw->saveimageext,draw->savefilecount-1);CHKERRQ(ierr);
  image = SAWs_images;
  while (image) {
    const char *name = image->filename;
    const char *ext  = image->ext;
    if (draw->savesinglefile) {
      ierr = PetscSNPrintf(body+len,4086-len,"<img src=\"%s%s\" alt=\"None\">",name,ext);CHKERRQ(ierr);
    } else {
      ierr = PetscSNPrintf(body+len,4086-len,"<img src=\"%s/%s_%d%s\" alt=\"None\">",name,name,image->count,ext);CHKERRQ(ierr);
    }
    ierr = PetscStrlen(body,&len);CHKERRQ(ierr);
    image = image->next;
  }
  ierr = PetscStrcat(body,"<br>\n");CHKERRQ(ierr);
  if (draw->savefilecount > 0) PetscStackCallSAWs(SAWs_Pop_Body,("index.html",1));
  PetscStackCallSAWs(SAWs_Push_Body,("index.html",1,body));
  PetscFunctionReturn(0);
}

PetscErrorCode  PetscLs(MPI_Comm comm,const char libname[],char found[],size_t tlen,PetscBool  *flg)
{
  PetscErrorCode ierr;
  size_t         len;
  char           *f,program[PETSC_MAX_PATH_LEN];
  FILE           *fp;

  PetscFunctionBegin;
  ierr   = PetscStrcpy(program,"ls ");CHKERRQ(ierr);
  ierr   = PetscStrcat(program,libname);CHKERRQ(ierr); 
#if defined(PETSC_HAVE_POPEN)
  ierr   = PetscPOpen(comm,PETSC_NULL,program,"r",&fp);CHKERRQ(ierr);
#else
  SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP_SYS,"Cannot run external programs on this machine");
#endif
  f      = fgets(found,tlen,fp);
  if (f) *flg = PETSC_TRUE; else *flg = PETSC_FALSE;
  while (f) {
    ierr  = PetscStrlen(found,&len);CHKERRQ(ierr);
    f     = fgets(found+len,tlen-len,fp);
  }
  if (*flg) {ierr = PetscInfo2(0,"ls on %s gives \n%s\n",libname,found);CHKERRQ(ierr);}
#if defined(PETSC_HAVE_POPEN)
  ierr   = PetscPClose(comm,fp);CHKERRQ(ierr);
#else
  SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP_SYS,"Cannot run external programs on this machine");
#endif
  PetscFunctionReturn(0);
}

/*@C
    PetscViewerStringSPrintf - Prints information to a PetscViewer string.

    Logically Collective on PetscViewer (Hmmm, each processor maintains a separate string)

    Input Parameters:
+   v - a string PetscViewer, formed by PetscViewerStringOpen()
-   format - the format of the input

    Level: developer

    Fortran Note:
    This routine is not supported in Fortran.

   Concepts: printing^to string

.seealso: PetscViewerStringOpen(), PetscViewerStringGetStringRead(), PetscViewerStringSetString(), PETSCVIEWERSTRING
@*/
PetscErrorCode  PetscViewerStringSPrintf(PetscViewer viewer,const char format[],...)
{
  va_list            Argp;
  size_t             fullLength;
  size_t             shift,cshift;
  PetscErrorCode     ierr;
  PetscBool          isstring;
  char               tmp[4096];
  PetscViewer_String *vstr = (PetscViewer_String*)viewer->data;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(viewer,PETSC_VIEWER_CLASSID,1);
  PetscValidCharPointer(format,2);
  ierr = PetscObjectTypeCompare((PetscObject)viewer,PETSCVIEWERSTRING,&isstring);CHKERRQ(ierr);
  if (!isstring) PetscFunctionReturn(0);
  if (!vstr->string) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ORDER,"Must call PetscViewerStringSetString() before using");

  va_start(Argp,format);
  ierr = PetscVSNPrintf(tmp,4096,format,&fullLength,Argp);CHKERRQ(ierr);
  va_end(Argp);
  ierr = PetscStrlen(tmp,&shift);CHKERRQ(ierr);
  cshift = shift+1;
  if (cshift >= vstr->maxlen - vstr->curlen - 1) cshift = vstr->maxlen - vstr->curlen - 1;
  ierr = PetscStrncpy(vstr->head,tmp,cshift);CHKERRQ(ierr);
  vstr->head   += shift;
  vstr->curlen += shift;
  PetscFunctionReturn(0);
}